Device for controlled application of compacting forces in powder press

ABSTRACT

A plurality of horizontally retractable wedge members are mounted in vertically registered relationship on a die platen and on at least one lower punch platen positioned therebelow, which platens are both supported in a floating manner. A push rod extending vertically through a slot formed in each wedge member on the die platen has a first contact member for sliding contact with the upper surface of that wedge member and a second contact member for sliding contact with the upper surface of the corresponding wedge member on the lower punch platen. The lower surfaces of these first and second contact members are shaped correspondingly to the sloping upper surfaces of the wedge members whereby, when the push rods are forced downward upon descent of an upper punch into the die cavity of the powder press, the vertically registered pairs of wedge members are made to retract against regulated pressure offered thereto by hydraulic power cylinders, thereby permitting the upper punch to move further downward.

United States Patent 1191 Watanabe et al. 1 Apr. 9, 1974 1 DEVICE FOR CONTROLLED APPLICATION 3,664,784 5/1972 Sibley 425/78 OF COMPACTING FORCES IN POWDER PRESS Primary Examiner-J. Howard Flint, Jr. [75] lnvefitorsz Takashi Watanabe, Kawaguchi; Attorney, Agent, or Fzrnz-Wenderoth, Lmd & Ponack Tatsuichi Yokoyama, Urawa, both of Japan [57] ABSTRACT [73] Assignee: Tamagawa Kikai Kinzoku A plurality of horizontally retractable wedge members Kabushiki Kaisha, Tokyo, Japan are mounted in vertically registered relationship on a die platen and on at least one lower punch platen posi- [22] Flled' Sept 1972 tioned therebelow, which platens are both supported [2]] Appl. No.: 289,233 in a floating manner. A push rod extending vertically through a slot formed in each wedge member on the die platen has a first contact member for sliding [30] Foreign Application Pnomy Data contact with the upper surface of that wedge member May 12, 1972 Japan 4736026 and a Second Contact member for sliding Contact with the upper surface of the corresponding wedge member [52] US. Cl 425/78, 425/214, 425/355, on the lower punch platen The lower surfaces of 425/338 425/415 425/450 these first and second contact members are shaped [51] f 1329c 3/00 83Gb 11/02 1330b 15/00 correspondingly to the sloping upper surfaces of the [58] Field of Search 425/78 wedge members whereby, when the push rods are forced downward upon descent of an upper punch [56] References C'ted into the die cavity of the powder press, the vertically UNITED A E PATENTS registered pairs of wedge members are made to retract 3,168,759 2/1965 Johannigmon 425/78 against regulated pressure offered thereto by hydraulic 3,172,156 3/1965 power cylinders, thereby permitting the upper punch 3,337, l6 /1967 to move further downward. 3,464,089 9/1969 3,635,617 l/l972 Hara et al. 425/78 4 Claims, 8 Drawing Figures LLJ O O 0 0o 0 0 PATENTEBAPR 9:914

SHEEI 2 OF 8 T28 is 3 L ATENTEU APR 9 I974 SHEEI 5 BF 8 DEVICE FOR CONTROLLED APPLICATION OF COMPACTING FORCES IN POWDER PRESS BACKGROUND OF THE INVENTION This invention relates generally to powder presses for compacting powdered materials such as, typically, powdered iron, copper, ceramics and the like into articles of complex shape. More specifically, the invention is directed to a device for controlled application of compacting forces on the powdered material in such a powder press in order to make possible the production of homogeneously compacted articles.

There has been known a powder press comprising a single die platen and one or more lower punch platens supported by pneumatic power cylinders or the like in a floting or vertically reciprocable manner. During compacting operation these platens float downward until they are restrained by stop mechanisms of verious type. For fabrication of an article having a stepped configuration with this type of powder press, the upper punch is forced down onto a powdered material contained in a die cavity formed by the telescopic arrangement of a die carried by the die platen and a plurality of lower punches which may include the fixed lowermost punch.

The upper punch forced into the die cavity firstdepresses the floating lower punch or punches through the powdered material. As the compacting operation proceeds, the powdered material is subjected to uneven pressures under the downward force of the upper punch due to the varied depth of 'the'die cavity, so that there tend to exist local density differences in thearticle compacted in this manner.

When the powdered material in the die'cavity issubjected to uneven pressures during the compacting operation'because of the differences in-effect of the compressing forceof the upper punch, there usually occur flows of the material toward the less affected parts thereof. It will be apparent that, if such flows occur, parts of lower density tend to be produced inthe powdered material. Such parts are fixed substantially as they are as the compacting'op'erationproceeds because the fluidity of the powdered material is rapidly decreased after the material has been compressed to some degree. Thus, local parts of lower density will inevitably be produced in the compacted article. Such density differences give riseto dimensional fluctuations in the succeeding sintering process operation or to decreased strength of the end products.

SUMMARY OF THE INVENTION In view of the above stated difficulties of the .prior art, it is an object of the'present invention to provide a novel device for controlled application of compacting pressures to a powdered material in a powder press, whereby the powdered material can be homogeneously compacted into an article having a complex stepped configuration.

Another object of-the invention is to providea device of the character referred to, which is easily-adjustable in such a manner that the density, and "therefore the strength, of the flanged or similarly enlarged portion of the workpiece can be argumented'as desired.

According to the'present invention,briefly summarized, there is provided a device for controlledapplication of compacting pressures to a powdered material in a powder press of the type including a vertically reciprocable upper punch, a floating die platen carrying a die, at least one floating punch platen carrying a movable punch, a stationary punch disposed in axial alignment with the upper punch, the die and the movable and stationary punches being arranged telescopically to define adie cavity, and releasable stop means for the punch platen. Characteristically, the device of this invention comprises horizontally retractable wedge members respectively positioned on the die platen and the punch platen in vertically registered relationship, means operatively connected to each of the wedge members for providing regulated resisting force against the retracting motionthereof, push rod means passing vertically through a slot formed in the wedge member positioned on the die platen and extending downward, said push rod means having a first contact means for making sliding contact with the upper surface of the wedge member positioned on the die platen and a sec- 0nd contact means for making sliding contact with the upper surface of the wedge member positioned on the punch platen, the lower surfaces of the first and second contact means being formed correspondingly to the upper surfaces of the wedge members to cause retracting motion thereof when the push rod means are force downwardly, and depressing means rigidly attached to the upper punch to force the push rod means downward upon descent of the upper punch intothe die cavity.

The novel features which are considered as being characteristic of this invention are set forth in the appended claims. The invention itself, however, together with additional objects and advantages thereof, will be best understood from the following detailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION With particular reference to FIG. 1 of the drawings,

the framework of the powder press for which the'device of this invention is adapted essentially comprises an upper frame or casing 1, a lower frame or casing 2, and a plurality of columns 3 extending between the upper and lower casings. Within the upper casing 1 there are housed a drive motor and a crank mechanism,

not shown, which cooperate to vertically reciprocate a ram 5 having an upper punch 4'extending downwardly therefrom.

Guide rods 6, also vertically extending between the upper and lower casings l and 2, floatingly or vertically reciprocably support a die platen 7 ahd, therebelow, a

punch platen 8. This punch platencarries a first lower punch 9 in axial alignment with the upper punch4. A second lower punch 10 also axiallyaligned with the upper punch 4 is fixedly mounted on the'lower casing 2. A control panell is provided to automatically control the entire operation of this punch press in accordance with the prior art.

As illustrated in greater detail in FlG. 2, these two lower punches 9 and 10 are arranged in telescopic relationship with a die 12 rigidly carried by the die platen 7, defining a die cavity into which a powdered material P is fed to be compacted to the desired shape upon decent of the upper punch 4, as hereinafter described in more detail. It is assumed that the die platen 7 and the punch platen 8 are suitably supported in a known manner, as for example by pneumatic power cylinders or the like.

The punch platen 8 is formed with -a bore 80 therethrough in axial alignement with the upper punch 4. Within this bore there is turnably mounted a worm wheel 14 to be rotated by a worm 13, the worm wheel being internally threaded to engage the corresponding external threads on a punch support 16 of hollow cylindrical shape received in the bore 8a and made capable of vertical motion only by a detent 15 engaging the support 16.

Fixedly mounted on this support' 16 is the aforesai first lower punch 9 of substantially hollow cylindrical shape. By turning the worm 13 from the outside by any suitable means the support 16 and hence the first lower punch 9 can be verticallyadjusted in position through the worm wheel 14. The second lower punch 10,

fixedly mounted on the upper wall 2a of the lower casing 2, extends'upwardly through the support 16 and the first lower punch 9, and has its upper end portion slightly increased in diameter to make slidable contact with the inner surface of the first lower punch 9.

The punch platen 8 has a plurality of stop rods 17 rigidly secured thereto, only one of such stop rods being shown in FIG. 2. These stop rods extend downward through the upper wall 2a of the lower casing 2 with suitable clearance and are each inserted centrally into a boxlike housing 18 mounted therein. The lower end of each stop rod is symmetrically tapered at 17a into the substantial shape of the letter V.

The housings 18 are all constructed identically, and each has a leg 19 of cylindrical shape extending downward from the center of its bottom, the leg 19 being externally threaded to engage the internal threads formed on a gear 21 supported in an intermediate wall 2b of the lower casing 2 so as to be capable of rotation only. A pin 20 also extends downward from each housing 18 and is slidably inserted into a bore 22. formed through the intermediate wall in order to prevent the rotation of the housing. Hence, by turning the gear 21 by suitable means, the positions of the housings 18 are vertically adjustable.

Within each of the housings 18, there are provided a cooperative pair of wedge members 23a and 23b having upper surfaces inclined toward each other as shown in the drawing to conform to the tapered lower end of each stop rod 17. These wedge members, slidable toward and away from each other within the housing, are urged toward each other by springs or the like (not shown). Transverse slots are formed correspondingly on the bottom surfaces of the wedge members 23a and 23b, in such a manner that when these wedge members are brought closest to each other, the slots are completely aligned into a single slot 24 which intersects the vertical axis of the stop rod 17 at right angle thereto.

A latch 27, movable into and out of the aligned slot 24, is slidably received in an axial bore 25 of the leg 19 and is urged upwardly by a spring 26. The upper surface of this latch is in contact with the lower end of a push rod 28 extending with suitable clearance through the wedge members 23a and 23b and the stop rod 17. The upper end of the push rod 28 is inserted into a bore 70 formed vertically through the die platen 7 and is below the level of the upper surface of the die platen.

Platen control mechanisms generally indicated by numeral 29 are provided for the die platen 7 and the punch platen 8 in positions symmetrically opposed with respect to the axis of the die 12, only one of the platen control mechanisms being shown in the drawings. As illustrated, the die platen 7 and the punch platen 8 are provided with worm wheels 32 and 33 to be rotated by worms 30 and 31,- respectively, the worm wheels being mounted within the platens so as to be capable of rotation only, These worm wheels 32 and 33 are internally threaded to engage the external threads on legs 36 and 37 extending downward from mountes 34 and 35, respectively. Rods 38 and 39 also extending downward from the mounts are slidably fitted into bores 40 and 41, respectively, formed vertically through the die platen 7 and the punch platen8 to prevent the rotation of the mounts. I

Fixedly supported on the mounts 34 and 35 are hydraulic power cylinders 42 and 43- having piston rods .44 and 45 extending horizontally therefrom to be securely connected to wedge members 46 and 47, respectively, which are slidable on their respective mounts and which have their upper surfaces inclined downwardly toward the die 12. The upper wedge member 46 has a slot 46a extending in the direction of its sliding movement, and a push rod 48 slidably inserted into the leg 36 of the mount 34 is received in this slot 46a. The push rod 48 is fixedly provided with a contact member 49 of an enlarged cross section which is in slidable contact with the inclined upper surface of the wedge member 46. The push rod 48 is also provided with another contact member 50 at its lower end for making sliding contact with the upper surface of the wedge member 47. The lower surfaces of these contact members are shaped correspondingly to the upper surfaces of the wedge members 46 and 47 to cause horizontal retracting motion thereof when the push rod 48 is forced downward, as hereinafter described in more detail. The fluid chambers of the hydraulic power cylinders 42 and 43 are connected to a suitable source of fluid pressure via pressure regulator valves 51 and 52, respectively.

The ram 5 is fixedly provided with an enlarged depressing part 53 at its lower end which is adapted for depressing the push rod 48 upon descent of the ram 5. i

The reference numeral 54 given in FIGS. 3 to 8 indicate an ejection rod capable of vertical displacement.

by the die 12, the first lower punch 9 and the second lower punch 10.

In FIG. 3 the upper punch 4 is lowered with the ram 5 into the die cavity to start compacting the powdered material P contained there in. The enlarged part 53 at the lower end of the ram 5 also descends onto the push rod 48 to depress the contact member 49 against the wedge member 46. The die platen 7, floatingly supported by the guide rods 6 as aforesaid, is thus caused to move downward with the upper punch 4.

As the ram 5 further descends in its compacting stroke, as in FIG. 4, the contact member 50 at the lower end of the push rod 48 moves into contact with the inclined upper surface of the wedge member 47 on the punch platen 8. Because now the first lower punch 9 also start descending with the punch platen 8, the stationary second lower punch must at this stage withstand the full load of the upper punch 4, so that part of the powdered material within the die cavity shifts in the directions of the arrows as the compacting operation proceeds.

When, as seen in FIG. 5, the stop rod 17 secured to ,the punch platen 8 is succeedingly lowered into contact with the upper surfaces of the wedge members 23a and 23b within the housing 18, the punch platen 8 and, therefore, the first lower punch 9 stop descending.

The ram 5 still continues descending to cause, on the one hand, the contact member 50 of the push rod 48 to press against the wedge member 47 on the punch platen 8 now prevented from downward motion by the stop rod 17. The wedge member 47 thus retracts horizontally against the pressure exerted by the hydraulic power cylinder 43 under the control of the pressure regulator valve 52, permitting the push rod 48 to move downward with its contact member 50 in sliding contact with the wedge member 47, so that the upper punch 4 further descends toward the first lower punch 9 now retained in its lowermost position by the stop rod 17 and toward the second lower punch 10 fixedly supported on the lower casing 2. This situation is as depicted in FIG. 6.

On the other hadn, as illustrated in the same figure, the wedge member 46 on the die platen 7 is caused to retract by the downward pressure of the ram 5 against the pressure of the hydraulic cylinder 42, which is regulated by the pressure regulator valve 51 to suitably control the downward pressure being applied to the die platen through the wedge member 46. Accordingly, the die 12 floats downward at a speed different from that of the upper puch 4. Accordingly, the powder to form the flange portion of the article is compacted by the downward and upward relative forces simultaneously exerted thereto by the upper punch 4 and the first lower punch 9. As the upper punch 4 descends to its predetermined lowermost position, the compacting operation of the powdered material is completed.

For ejection of the article 8 thus obtained, the ejection rods 54 are lowered onto the die platen 7 by a suitable cam mechanism following the upward return stroke of the upper punch 4, as illustrated in FIG. 7. When the die platen 7 is succeedingly forced downwardly by the ejection rods 54 until its upper surface becomes flush with the upper surface of the first lower punch 9, the lower surface of the die platen comes into contact with the upper end of the stop rods 17. The push rods 28 within the stop rods 17 are now depressed by the ejection rods 54, causing the latches 27 to move out of the aligned slots 24 of the wedge members 23a and 23b against the springs 26 and thus unlocking these wedge members within their respective housings 18.

As seen in FIG. 8, the stop rods 17 are now free to move further downwardly with its tapered lower end in sliding contact with the correspondingly inclined upper surfaces of the wedge members 230 and 23b. As a consequence, the ejection rods 54 continue to depress the die platen 7 and the punch platen 8 until the upper surfaces of the die 12 and the first lower punch 9 become flush with the upper surface of the second lower punch 10. The ejection of the article S is thus completed.

After removal of the article S, the ejection rods 54, the die platen 7 and the punch platen 8 are all elevated to their initial positions illustrated in FIG. 2, and the' above described sequence of operations may now be restarted. The worms 30 and 31 mounted in the die platen and the punch platen may be suitably driven from the outside to adjust the vertical positions of the mounts 34 and 35 and of the various means placed thereon in accordance with the above described operative features of this invention.

It will be readily understood that a plurality of punch platens may be provided, instead of the single punch platen 8 of the exemplified embodimentof this invention, without departing from the scope of the invention. Further, the fluid pressures supplied to the power cylinders 42 and 43 may be regulated not only by the pressure regulator valves 51 and 52 but, in some cases, by electromagnetic valves positioned adjacent the inlet ports of the power cylinders. The fluid pressures will then be regulated byv communicating the fluid chambers within the cylinders to the atmosphere through the electromagnetic valves.

We claim: 1. In a powder press for compacting powdered material into an article having a substantially stepped configuration, said powder press having a vertically reciprocable upper punch, a floating die platen carrying a die, at least one floating punch platen carrying a movable lower punch, a stationary lower punch disposed in axial alignment with said upper punch, said die and said movable and stationary lower punches being arranged telescopically to define a die cavity, and releasable stop means for said punch platen, the improvement com prising:

horizontally retractable wedge members respectively positioned on said die platen and said punch platen in vertically registered relationship;

means operatively connected to each of said wedge members for providing regulated resisting force against the retracting motion thereof;

push rod means passing vertically through a slot formed in said wedge member positioned on said die platen and extending downward;

said push rod means having a first contact means for making sliding contact with the upper surface of said wedge member positioned on said die platen and a second contact means on the lower end thereof for making sliding contact with the upper surface of said wedge member positioned on said punch platen;

the lower surfaces of said first and second contact means being formed correspondingly to the upper surfaces of said wedge members to cause retracting motion thereof when said push rod lmeans are forced downward; and

depressing means rigidly attached to said upper punch to force said push rod means downward upon descent of the upper punch into said die cavity.

2. The improvement according to claim 1 in which said means for providing regulated pressure against the retracting motion of said wedge members comprises hydraulic power cylinder means positioned adjacent each of said wedge members, said hydraulic power cylinder means having a piston rod projecting outward therefrom to be coupled to the adjacent wedge member, and a pressure regulator valve interposed between said hydraulic power cylinder means and a source of hydraulic pressure.

3. The improvement according to claim 1, further comprising means for adjusting the vertical position of each of said wedge members relative to the corresponding one of said die platen and said punch platen, said means comprising a mount on which each of said wedge members is slidably mounted, an externally threaded leg extending from said mount into a vertical bore formed through the corresponding one of said die platen and said punch platen, a worm wheel having inv mount. 

1. In a powder press for compacting powdered material into an article having a substantially stepped configuration, said powder press having a vertically reciprocable upper punch, a floating die platen carrying a die, at least one floating punch platen carrying a movable lower punch, a stationary lower punch disposed in axial alignment with said upper punch, said die and said movable and stationary lower punches being arranged telescopically to define a die cavity, and releasable stop means for said punch platen, the improvement comprising: horizontally retractable wedge members respectively positioned on said die platen and said punch platen in vertically registered relationship; means operatively connected to each of said wedge members for providing regulated resisting force against the retracting motion thereof; push rod means passing vertically through a slot formed in said wedge member positioned on said die platen and extending downward; said push rod means having a first contact means for making sliding contact with the upper surface of said wedge member positioned on said die platen and a second contact means on the lower end thereof for making sliding contact with the upper surface of said wedge member positioned on said punch platen; the lower surfaces of said first and second contact means being formed correspondingly to the upper surfaces of said wedge members to cause retracting motion thereof when said push rod 1means are forced downward; and depressing means rigidly attached to said upper punch to force said push rod means downward upon descent of the upper punch into said die cavity.
 2. The improvement according to claim 1 in which said means for providing regulated pressure against the retracting motion of said wedge members comprises hydraulic power cylinder means positioned adjacent each of said wedge members, said hydraulic power cylinder means having a piston rod projecting outward therefrom to be coupled to the adjacent wedge member, and a pressure regulator valve interposed between said hydraulic power cylinder means and a source of hydraulic pressure.
 3. The improvement according to claim 1, further comprising means for adjusting the vertical position of each of said wedge members relative to the corresponding one of said die platen and said punch platen, said means comprising a mount on which each of said wedge members is slidably mounted, an externally threaded leg extending from said mount into a vertical bore formed through the corresponding one of said die platen and said punch platen, a worm wheel having internal threads to engage the external threads of said leg and supported in the wall of said vertical bore so as to be capable of rotation only, and a driving worm in mesh with said worm wheel.
 4. The improvement according to claim 3, including a rod extending downward from each of said mount and slidably inserted into another vertical bore formed in the corresponding one of said die platen and said punch platen in order to prevent rotation of said mount. 